I have finally done a factory reset. It seems to have solved some issues, but others are outstanding. Seems to be solved: - Unstable applications (flashing and crashing, including Gmail). - Unstable folders (flashing, crashing and all icons on the desktop disappearing). Unsolved: - The GPS does not work (this is a new issue I had not noticed before). - System update does not work (indicates that network coverage is insufficient despite the signal being strong and staying beside the wireless router). - Wifi is unstable (it does not seem to disconnect anymore, but the strength varies a lot, despite I am not moving and other devices show a constant and strong signal). - One time, the device refused to change the orientation, despite I tried several time (had to reboot). Any suggestion on solving these issues?